Liquid propellant machine gun



Filed Oct. 9, 1961 W m 5, W E m MA J Z A.A.. am w mi mm m wv %\A 1 Am WYA v m/.|| fi k Nu 0 o United States Patent 3,138,990 LIQUID PROPELLANTMACHINE GUN Roy A. Jukes, Knoxville, Tenn, and Bernard A. Niemeier,

Richmond, Va., assignors, by mesne assignments, to

the United States of America as represented by the Secretary of the ArmyFiled Oct. 9, 1961, Ser. No. 143,983 3 Claims. (Cl. 89-7) This inventionrelates to a liquid propellant gun and more specifically to a liquidpropellant gun adapted for high rates of fire utilizing hypergolicpropellants.

Briefly, our invention comprises a block having an axially slidabledifferential piston which has an axial passage for the feed of theprojectiles to be fired. The piston has two shoulder portions whichslide in two bores in the block to act as feed means for two hypergolicpropellants which are fed into said bores. The forward face of thedifferential piston forms one wall of a combustion chamber and thehypergolic propellants are fed to the combustion chamber through orificepassages in the differential piston. These passages are made smallenough to obviate any necessity for propellant valves. Projectiles arefed axially from a magazine through the block and differential pistoninto the gun barrel by a feed piston actuated by the gun. The projectilein the barrel is propelled by the pressure generated by the burning ofthe hypergolic propellants and the other projectiles in the feed lineact as an obturator and take the place of a breech block.

An object of this invention is to provide a liquid propellant gunutilizing .hypergolic propellants.

Another object of the invention is to provide a liquid propellant gunhaving a differential piston to feed separate propellants to acombustion chamber through metering orifices in the piston.

Yet another object is to provide a liquid propellant gun having adifferential piston for supplying the propellants and a projectile feedmechanism operated by the differential piston.

A further object is to provide a gun in which projectiles are fed in anaxial line to the barrel and act as an obturator to obviate thenecessity of a breech block.

These and other objects will become more apparent when reference is hadto the following detailed description and drawing in which:

FIGURE 1 is an axial sectional view of our liquid propellant gun.

FIGURE 2 is a sectional view taken on the line 2- 2 of FIGURE 1 lookingin the direction of the arrows and illustrating the means which preventsretrograde projectile movement, and

FIGURE 3 is a sectional view taken on the line 3--3 of FIGURE 2.

With reference to the drawing there is shown a liquid propellant gunhaving a block made up of three sections 1, 2, 3 which are rigidlysecured together by any suitable means such as through bolts (notshown). The forward block section 3 has the internally threaded bore 4in which is received the gun barrel 5 and is further provided with thebore 6 which receives the collar 7 having an internal diameter equal tothe diameter of the barrel bore. The central block sectionZ is bored andreceives the sleeve member 8 which is provided with the internalshoulder 9 and the bores 10 and 11. The block section 1 is provided withthe bore 12 which is coaxial withbores 10 and 11 in the sleeve 8.Slidably received within the bores 1f), 11, 12 is the differentialpiston 13 having integral shoulder 14 slidable in bore 10 and attachedshoulder 15 slidable in bore 11. The differential piston 13 has thecentral longitudinal passage 16 for the passage therethrough ofprojectiles 3,138,990 Patented June 30, 1964 and reduced end portion 17.The forward portion of the differential piston is flared as indicated at18 and is provided with orifice channels 19 and 21) which pro videcommunication between the forward face of the piston and the bores 10and 11, respectively. The volume between the front face of thedifferential piston 13 and the block section 3 forms a combustionchamber 21.

The gun of this invention utilizes liquid propellants and preferablypropellants of the hypergolic type, i.e. those which spontaneouslyignite upon contact with one another. An example of hypergolic reactantsis hydrogen peroxide (H 0 and hydrozine (N H Obviously, such reactantscannot be premixed and must be fed to the combustion chamber 21separately.

The block section 1 is provided with recess 22 and block section 2 has amating recess 23. Mounted within the recesses 22 and 23 is the valveplug 24 having inlet passage 25 for one of the hypergolic reactants.Check ball 26 is received in the valve plug 24 and urged to closedposition by spring 27 seated in cup 28. The sleeve 8 is provided withpassage 29 which affords communication between inlet passage 25 and bore10. The block sections 2 and 3 are provided with corresponding matingrecesses 30 and 31, respectively, which receive the valve plug 32 havinginlet passage 33 for admission of the second hypergolic reactant. Checkball 34 is received in the valve plug 32 and urged to closed position byspring 35 received in cup 36. Passage 37 affords communication betweenthe inlet passage 33 and bore 11.

A piston stop mechanism is indicated in its entirety byreferencecharacter 38. Threadedly received in the block section 2 is thecup shaped member 39 having central post 40. Slidably mounted in theblock and sleeve 8 is the stop member 40 having the piston 41 formed onits upper end. The spring 42 surrounds the post 40 and reacts againstthe piston 41 to urge the stop member 40 downwardly. When thedifferential piston 13 is moved to the left from the position shown inFIGURE 1 the stop member 40 may move downwardly under the influence ofspring 42 in front of shoulder 14 to lock the piston in rearwardposition. The block section 2 is provided with passage 43 by whichpressure fluid can be admitted below the piston 41 to raise the stopmember 40 against the action of spring 42.

Threadedly connected to the rearward end of block section 1 is theprojectile feed mechanism 44. This feed mechanism forms the subjectmatter of a separate patent application butit will be described here inits relationship to the remainder of the gun.

The feed mechanism comprises a housing 45 having a centrally disposedprojectile feed channel 46 and integrally formed cylinder 47 coaxialwith the feed channel. The forward end of the housing 45 is providedwith a pilot extension 48 which slidably receives the rear end ofdifferential piston 13. A fluid tight projectile magazine 49 is mountedon the housing and communicates with the feed channel 46. The magazineis provided with a follower 50 slidable therein in sealed engagement andport 51 by which pressure fluid may be admitted to force the followerdownwardly. Slidably mounted in the housing is the feed plunger 52having the piston 53 connected thereto and. slidable in the cylinder 47.Gas pressure may be applied to the rear side of piston 53 through theport 54 in the cylinder.

1 47. Communication is provided between the front face of piston 53 andthe rear face of differential piston 13 by means of channels 55 in thehousing 45 and these channels are filled with an incompressible fluid.

As shown in FIGURES 2 and 3 the projectile feed mechanism is providedwith means to prevent retrograde motion of the projectiles after theyare fed. The houstherein begins to rise.

3 ing 45 is provided with a plurality of radially slidable stop plungers56. These .plungers are urged into the feed channel by gas pressureapplied to the upper sides thereof through ports 57 and the lower endsthereof are rearwardly bevelled as shown at 58. When a projectile is fedforwardly the plungers are cammed outw Wardly to permit passage of theprojectile and then snap inwardly by gas pressure to prevent reverseprojectile movement. I I

Operation In idle condition the differential piston 13 will be moved toleft from the position shown in FIGURE 1 and locked by stop member 46.To place the gun in operation, gas pressure is supplied to channel 43 toraise thestop member 40 and also to the ports 51, 54 and 57 oftheprojectile feed mechanism. Gas pressure applied to the feed plungerpiston 53 will move the plunger 52 to the right and feed a projectileinto the gun barrel 5. When the piston 53 moves to the right the liquidin channels 55 will act as a hydraulic link and move the differentialpiston 13 to the position shown in FIG- URE 1 by acting on the rear facethereof.

The hypergolic reactants are supplied under pressure to theinletpassages .25 and 33 and flow past the check valves into bores and 11,respectively. The volume of these bores is proportioned to provide ameasured amount of the propellants. The sleeve 8 is provided with anannular air channel 59 and the block section 2 has the scavenging port60 therein to prevent the passage of propellants from one bore to the.other.

The propellants now begin to feed from the bores 10 and 11 to thecombustion chamber 21 by way of the orifice channels 19 and 20,respectively. The diameter of these channels is selected to restrict thefeed rate to give the desired burning rate. In this manner the necessityof valves in these channels is obviated. As soon as the hypergolicreactants meet in combustion chamber 21 combustion is initiated and thepressure When this pressure has risen sufiiciently to overcome the gaspressure acting on piston 53 of the feed plunger and the inlet pressureof the .propellant, the differential. piston begins to move backwardly.This increases the pressure in the bores 10 and 11 and closes the inletcheck valves. The increased pressure on the propellants in the bores 10and 11 accelerates the feed thereof through the orifice channels 19 and2 0 and increases the rate of combustion until the piston has moved tothe rearward end of its travel. Incident to the rearward movement of thedifferential piston 13, the hydraulic link causes retraction of the feedplunger to permit another projectile to feed from the magazine 49 intothe feed channel 46.

When gas pressure is built up combustion chamber I 21 the projectilewhich is in the barrel is propelled forwardly at high speed. Theprojectiles occupying the space between the combustion chamber and feedmechanism are prevented from rearward movement by the plungers 56. Itwill be noted that the diameter of the projectiles and the diameter ofthe passage 16 are sub stantially the same so that the projectiles inthe passage act as an obturator and preclude the necessity of any breechblock mechanism.

' When the projectile clears the barrel of the gun the pressure in thecombustion chamber immediately drops off. The gas pressure acting on thefeed piston 53 now moves the feedplunger forward and through thehydraulic link also moves the differential piston 13 forwardj 1y so thatthe firing may automatically repeat.

'It will be apparent that the embodiment shown is only exemplary andthat various modifications in construction and arrangement may be madewithout departing from thescope of the invention as defined in thesubjoined claims.

We claim:

1. In a liquid propellant gun, the combination comprising, a compositeblock including an intermediate section, a forward section and arearward section, said sections having axial, aligned borestherethrough, a sleeve in said central section and having an internalannular shoulder therein, there being forward and rearward axial borestherein and disposed, one each, on each side of said shoulder, said lastnamed bores being coaxial with respect to said bores in said forward andrearward sections; a single differential piston mounted for axial reciprocation in said bores in said sleeve and said bore in piston havingmetering orifice channels communicating.

between said combustion chamber and said bores in said sleeve; valvemeans in said block for admitting hypergolic reactants to saidcombustion chamber through said channels, the increase in pressure fromcombustion of the hypergolic reactants in said combustion chamber beingeffective to move said'piston' rearwardly to accelerate, the

feed of said reactants into said combustion chamber; a

barrel connected to said forward section, said barrel having an axialbore of the same diameter as said passage in said piston and inalignment therewith; means connected to the rearward section forfeeding'projectiles into said passage in said piston and barrel; adifferential piston stop mechanism in said block for locking said pistonin a rearwardcocked position; scavenging means for said gun disposed insaid block sections for preventing passage of propellants from one ofsaid bores in said sleeve'to the other; and means for preventingretrograde motion of the projectiles after being fed into said pistonand disposed between said feeding means and said rearward sectioncomprising a series of inwardly urged, radially disposed plungers havingbeveled inner endswhereby when a projectile is fed forwardly, saidplungers are cammed outwardly and snap inwardly upon forward clearanceof'a projectile. l

2. In a liquid propellant gun as defined in claim 1, wherein saiddifferential piston stop mechanism comprises a plunger radially slidablein said intermediate block,=said plunger being projected in front ofsaid shoulder on said differential piston when said piston is in arearward position and spring means to urge said plunger inwardly, saidplunger being movable outwardly to free said shoulder by the applicationof fluid pressure to the under side thereof. a I j 3. In a liquidpropellant gun as defined in claim 1,

I wherein said scavenging means comprises an annular UNITED STATESPATENTS 2,965,000 Skinner Dec. 20, 1960 2,981,153 Wilson et a1 Apr. 25,1961 2,986,072 Hudson May 30, 1961

1. IN A LIQUID PROPELLANT GUN, THE COMBINATION COMPRISING, A COMPOSITEBLOCK INCLUDING AN INTERMEDIATE SECTION, A FORWARD SECTION AND AREARWARD SECTION, SAID SECTIONS HAVING AXIAL, ALIGNED BORESTHERETHROUGH, A SLEEVE IN SAID CENTRAL SECTION AND HAVING AN INTERNALANNULAR SHOULDER THEREIN, THERE BEING FORWARD AND REARWARD AXIAL BORESTHEREIN AND DISPOSED, ONE EACH, ON EACH SIDE OF SAID SHOULDER, SAID LASTNAMED BORES BEING COAXIAL WITH RESPECT TO SAID BORES IN SAID FORWARD ANDREARWARD SECTIONS; A SINGLE DIFFERENTIAL PISTON MOUNTED FOR AXIALRECIPROCATION IN SAID BORES IN SAID SLEEVE AND SAID BORE IN SAIDREARWARD SECTION, THERE BEING AN INTEGRAL SHOULDER THEREON, SAIDSHOULDER SLIDABLE IN THE REARWARD BORE OF SAID SLEEVE, A DETACHABLESHOULDER SECURED ON THE FORWARD END OF SAID PISTON AND SLIDABLE IN THEFORWARD BORE IN SAID SLEEVE, THERE BEING A CENTRAL AXIAL PASSAGE THROUGHSAID PISTON AND BEING IN ALIGNMENT WITH THE BORES IN SAID FORWARD ANDREARWARD SECTIONS, SAID DETACHABLE SHOULDER BEING FLARED TO FORM ACOMBUSTION CHAMBER BETWEEN THE FORWARD FACE OF SAID PISTON AND SAIDFORWARD SECTION, SAID PISTON HAVING METERING ORIFICE CHANNELSCOMMUNICATING BETWEEN SAID COMBUSTION CHAMBER AND SAID BORES IN SAIDSLEEVE; VALVE MEANS IN SAID BLOCK FOR ADMITTING HYPERGOLIC REACTANTS TOSAID COMBUSTION CHAMBER THROUGH SAID CHANNELS, THE INCREASE IN PRESSUREFROM COMBUSTION OF THE HYPERGOLIC REACTANTS IN SAID COMBUSTION CHAMBERBEING EFFECTIVE TO MOVE SAID PISTON REARWARDLY TO ACCELERATE THE FEED OFSAID REACTANTS INTO SAID COMBUSTION CHAMBER; A BARREL CONNECTED TO SAIDFORWARD SECTION, SAID BARREL HAVING AN AXIAL BORE OF THE SAME DIAMETERAS SAID PASSAGE IN SAID PISTON AND IN ALIGNMENT THEREWITH; MEANSCONNECTED TO THE REARWARD SECTION FOR FEEDING PROJECTILES INTO SAIDPASSAGE IN SAID PISTON AND BARREL; A DIFFERENTIAL PISTON STOP MECHANISMIN SAID BLOCK FOR LOCKING SAID PISTON IN A REARWARD COCKED POSITION;SCAVENGING MEANS FOR SAID GUN DISPOSED IN SAID BLOCK SECTIONS FORPREVENTING PASSAGE OF PROPELLANTS FROM ONE OF SAID BORES IN SAID SLEEVETO THE OTHER; AND MEANS FOR PREVENTING RETROGRADE MOTION OF THEPROJECTILES AFTER BEING FED INTO SAID PISTON AND DISPOSED BETWEEN SAIDFEEDING MEANS AND SAID REARWARD SECTION COMPRISING A SERIES OF INWARDLYURGED, RADIALLY DISPOSED PLUNGERS HAVING BEVELED INNER ENDS WHEREBY WHENA PROJECTILE IS FED FORWARDLY, SAID PLUNGERS ARE CAMMED OUTWARDLY ANDSNAP INWARDLY UPON FORWARD CLEARANCE OF A PROJECTILE.